The present invention is concerned with a snow removal apparatus for removing snow from a light fixture protruding from the ground, such as taxi-lights located on both sides of an airport runway. More particularly, the invention is directed to a snow removal apparatus of the type to be mounted on a vehicle.
Airport taxi-lights are to be distinguished from landing-lights in that they are less bulky and of more fragile construction and therefore are more susceptible to damage than are landing-lights during clearing of the runways in winter. Such taxi-lights generally have a diameter of about four inches and protrude above the ground to a height of about one foot; the base is made of white metal and thus can be easily broken by an inadvertent blow on the light. A series of these taxi-lights extend along each side of the runway.
In the clearing process of an airport runway, the runway itself is first cleared using conventional machines such as snow-ploughs and/or snow-blowers which move along the runway. The bulk of the snow adjacent one series of taxi-lights is next removed using such machines which move along a sinusoidal path so as to contour each light on one side thereof and the same sinusoidal path is followed on the other side. Thereafter, the remainder of the snow is manually removed from each light as well as from the immediate surrounding area so as to enable the light to viewed from a distance. This cleaning procedure is repeated from the other series of taxi-lights located on the other side of the runway. Since these lights are often completely covered with snow and hidden from the view as a result of a snow fall or of gusting winds piling up snow thereover, many lights do get damaged in the clearing process. Statistics show that as many as 600 taxi-lights or more per airport are destroyed every winter, at a cost of about $100 per unit, including labour for replacing the lights. This of course adds to the already high costs of labour for clearing the lights of snow.
Vehicles equiped to blow air against an airport runway to clear same have been proposed in U.S. Pat. No. 3,228,125 and in Canadian Pat. No. 671,186. These known runway cleaning machines use jet engines for discharging air at very high velocities so as to effectively and rapidly remove snow, slush, loose ice and water from the runway. Such air-blowing machines, however, cannot be used to remove snow from taxi-lights since the latter cannot withstand the pressure of the high velocity air produced and would thus break away. On the other hand, if the velocity of the air is reduced sufficiently to avoid breaking the lights, the pressure thereof is insufficient to clear a suitable area of snow around each light.